The invention relates to a method of detecting a watermark embedded in an information signal, comprising a correlation step for correlating said signal and an applied watermark, and an evaluation step for evaluating the result of said correlation. The invention also relates to a method for carrying out said method.
Watermarks are perceptually invisible messages embedded in multimedia content such as audio, still images, animations or video. They comprise information, for example, about the source or copy right status of documents or audiovisual programs. Watermarks can be used to provide legal proof of the owner of the copyright. They allow tracing of piracy and support the protection of intellectual property.
A known method of detecting a watermark embedded in an information signal comprises a correlation step for correlating said signal and an applied watermark. The result of said correlation is then evaluated. For example, if the amount of correlation is larger than a predetermined value, the applied watermark may be considered to be the watermark embedded in the signal. Alternatively, a number of successive correlation steps can be carried out for different applied watermarks. The applied watermark yielding the largest correlation is then considered to be the watermark embedded in the signal. The above citations are hereby incorporated in whole by reference.